WO2018086910A1

WO2018086910A1 - Receiver having absorber modules

Info

Publication number: WO2018086910A1
Application number: PCT/EP2017/077509
Authority: WO
Inventors: Johannes Trautner
Original assignee: Kraftanlagen Muenchen Gmbh
Priority date: 2016-11-11
Filing date: 2017-10-26
Publication date: 2018-05-17
Also published as: ES2859491T3; CY1123923T1; PT3538823T; CN208139605U; EP3538823B1; AU2017356608A1; EP3538823A1; DE102016121654B3

Abstract

The invention relates to a receiver of a solar energy recovery plant (100), comprising a support structure (7), which carries a plurality of absorber modules (11) on a receiver front side, each comprising a retaining tube (21), which engages in a guide tube (41) of the support structure (7) such that a ring gap (50) is formed between the retaining tube (21) and the guide tube (41), through which return air flows to the receiver front side during operation in order to cool the support structure (7) and/or the affected absorber module (11). At least one throttling return air aperture (43) is arranged in at least one of the ring gaps (50), which defines a mass flow of the return air flowing through the affected ring gap (50) to the receiver front side.

Description

Receiver with absorber modules The present invention relates to a receiver for solar energy generation systems according to the preamble of claim 1.

In the document DE 197 44 541 C2, a solar receiver is described which has a plurality of absorber modules. The absorber modules each contain a porous absorber body, which faces the incident solar radiation. Through the absorber body air is sucked in, which heats up as it flows through the absorber body.

The receiver is suitable for large power generation plants, where, for example, numerous heliostats are distributed in a field that reflect solar radiation on the receiver. Thus, a high radiation concentration is produced at the receiver, which results in temperatures in the range of up to 1100 ° C. at the absorber module. In the prior art solar receiver, a support structure is provided which carries numerous absorber modules. Each absorber module consists of an absorber head and an absorber body held by the absorber head. The absorber body is followed by a hot air duct. The generated hot air is used, for example, for the operation of working machines such as e.g. Turbines for power generators uses and cools down, but still contains residual heat or has a usable temperature difference compared to the ambient temperature.

To use this residual heat or usable temperature difference, the air is returned to the solar receiver and a part of the air along the walls of the hot air ducts along to cool them. The return air flows between the absorber modules to exit at the front side towards the front. It is then sucked back into the absorber body together with the ambient air. The solar radiation concentrated on the receiver is normally not distributed homogeneously. Rather, the radiation flux density is approximately in the form of a Gaussian distribution.

Each absorber module is associated with a hot air mass flow throttling diaphragm, by means of which the hot air mass flow of the radiation flux density is adjusted. As a result, the air mass flow ratio of the air flowing through the absorber module air mass flow of the process air is adjusted relative to the air mass flow through the other absorber modules, whereby an optimized mass flow distribution of the hot air flows flowing from the absorber modules is achieved. In addition, the absorber modules are also flowed around by the return air and thus cooled. The temperature of the absorber modules thus also depends on the temperature and the mass flow of the return air. For this reason, the mass flow of the return air is set individually for each module, thus further optimizing the mass flow and temperature distribution of the absorber modules. Due to the return air flowing along the absorber, not only the temperature of the absorber modules is influenced, but also the temperature distribution of the support structure is determined. An individual adjustment of this mass flow ensures that areas of this structure which are highly thermally stressed are sufficiently cooled, and thus a thermal overloading is precluded, and, for example, additional cooling or the use of high-temperature-resistant materials is unnecessary.

In order to ensure on the one hand, the minimum cooling of the support structure and on the other to keep the heat loss between the two air streams as low as possible, a very accurate adjustment of the recirculation mass flow is necessary. Furthermore, the amount of hot and return air for each absorber module must be matched appropriately to ensure the best possible re-absorption of the return air. Thus, the highest possible recovery of the residual heat of the return air is achieved and maximizes the efficiency of the solar energy recovery plant.

The invention has for its object a receiver of the type mentioned in the introduction with a structurally easy to implement possibility of setting the return flow mass flow to create.

This object is achieved by the receiver with the features of claim 1. The receiver according to the invention for energy sources in such a way has a supporting structure which carries absorber modules. The absorber modules each contain a front absorber body, which is followed by a hot air duct. The individual absorbers are respectively flowed through with process air, which is supplied as a heat transfer medium to a consumer. After the consumer, the cooled process air is fed back to the receiver as so-called return air via a Luftmckführungssystem at least partially. Within the support structure, this return air is divided without mixing with the hot air to the individual absorber. It flows in return air ducts along the holding tube and the absorber in front of the absorber body. The invention is characterized in that in each of the return air ducts of each or all of the absorber modules, at least one orifice restricting the return air mass flow is arranged, which determines the mass flow of the return air of the relevant absorber. Through the use according to the invention of the same or also different return air apertures in at least one of the annular gaps assigned to the absorber modules, the ratio of the mass flows in the annular gaps can be set.

The ratio of the mass flows of the return air of the absorber modules can be adjusted by means of the return air apertures and the cooling of those modules and the receiver structure can be adapted to the distribution of the radiation power. At the same time, the internal heat loss between hot and return air is significantly reduced while ensuring the minimum cooling of the absorber and

Supporting structure. Furthermore, the recirculation mass flow is hereby adapted to the respective hot air mass flow of the absorber and optimum return of the air is achieved. This ensures maximum efficiency of the solar energy recovery system. The diaphragms are determined on the basis of the mainly existing radiant flux density division and the temperature distribution of the support structure designed in the main load case and it is achieved a much improved distribution for the majority of the operating time.

The design of the panels as simple sheet metal parts is designed so that the flow area of the return air is reduced from hardly to very much and thus results in a large adjustment range.

By an asymmetrical design of the aperture even a direction-dependent flow throttling can take place. This directional dependence of the throttling is necessary if the flow is not formed symmetrically in front of the diaphragm and after the aperture as uniform as possible flow profile is required. Furthermore, the possibility of variation of the mass flow setting can be significantly increased by the combination of two diaphragms.

Another essential feature of the diaphragms described is the ease of installation and interchangeability, since the annular gap between the hot air tube and the guide tube is easily accessible on one side from the outside and the panels can be secured in this gap, for example, via an easily detachable connection. Due to the good accessibility, it is possible to assemble these throttle components only after installation of the receiver in a tower of the solar power plant, and thus significantly reduce the susceptibility to errors of assembly, since the cost of a reliable assignment of the panels is much lower. Furthermore, it is possible in such an embodiment of the throttle elements to exchange all or only part of the panels within the scope of a maintenance, without having to dismantle essential parts of the receiver. A rapid adaptation of the individual mass flows of the return air based on Betri ebserfahrungen is possible.

The diaphragm according to the invention can be designed as a perforated ring, which is positioned for the most part within the annular gap between the hot air tube and the guide tube. But it can also be designed so that a large part of the diaphragm is in the form of a retaining ring outside the guide tube and the Rückführmassen- current only by small interference surfaces, which are positioned within the annular gap and are formed by aperture elements, is regulated. Furthermore, these two described embodiments can also be designed asymmetrically. Further advantages and advantageous embodiments will become apparent from the description, the drawings and the claims.

Embodiments of a receiver according to the invention are shown schematically simplified in the drawing and are explained below with reference to the accompanying drawings. It shows:

Fig. 1 is a schematic view of a solar energy production plant with a

inventive receiver,

2 shows a schematic view of one of a plurality of receiver modules, of which there is essentially a support structure and an air duct of the receiver according to the invention,

3 shows a schematic longitudinal section through the receiver module with three absorber modules and return air apertures as well as details C and D;

4 shows a first embodiment of a return air aperture.

5 shows a second embodiment of a return air diaphragm. and FIG. 6 shows a third embodiment of a return air diaphragm;

In Fig. 1, a solar energy recovery plant 100 is shown schematically simplified. Sunlight is reflected by the heliostat 1 10 of a heliostat field 120 on the receiver 1 according to the invention. The receiver 1 is designed as an open volumetric receiver, wherein air from the area in front of the front side la of the receiver is sucked in and forms the process air. The process air is heated by the receiver 1 and fed via hot air lines 130 to a consumer. The consumer may for example be a steam generator 140 with a conventional steam cycle 150 or heat storage 160. Furthermore, the heated process air can be used as process heat, for example, to represent hydrogen. Via an air return system 170, the cooled process air is supplied to the receiver 1. There it is used completely or only partially for cooling the receiver and finally led in front of the front side la and sucked there mostly as process air. In Fig. 2, a receiver module 5 is shown schematically simplified. Such receiver modules are both an essential part of a supporting structure of the receiver 1 according to the invention, as well as the main component of the receiver-internal air duct. The receiver module 5 has on a front side a plurality of holes 9, in which the absorber modules 11 are inserted. At the back (in Fig. 2 below) of the receiver module 5 are located outlets 15 for the hot air, which are in communication with the absorber modules 1 1. The return air 35 is supplied to the side of the receiver module 5 and evenly distributed between the absorber modules 11 blown in front of the front of the receiver module 5. In Fig. 3 is a receiver module of the inventive receiver including three

Absorber modules 1 1 shown in section. As can be seen, an absorber module 1 1 consists of a cup-shaped absorber body 13 which holds an absorber head 17. The absorber body 13 opens into a hot air duct 44, wherein the mass flows of each individual Absorbermo- module 1 1 are set in relation to other absorber mass flows of the receiver 1 by differently running hot air apertures 39. The absorber body 13 is inserted into a holding tube 21 and connected thereto with a support structure 7. The holding tube 21 is thermally insulated by an insulation 37 against the hot air duct 44.

With the return air 35 from the air return system 170, both the support structure 7 and the guide tubes 41 are cooled. In order to avoid a thermal overload in the holding tubes 21, a portion of the return air flows through flow channels 45 in the guide tubes 41 in an annular gap between the respective holding tube 21 and the respective guide tube 41. At the end of this annular gap sits a recirculation orifice 43, the throttles the amount of air flowing in the respective annular gap 50. After passing through the return air apertures 43, the air enters an intermediate space 40 between the absorbers and continues from there via gaps between the absorber bodies 13 in front of the front side la.

The pressure loss of the return orifice 43 is substantially greater than that of the flow channels 45 in the guide tubes. Accordingly, the mass flow of the return air flowing through the gap between the holding tube 21 and the guide tube 41 and the Holding tubes 21 and the absorber body 13 cools, determined by the return air apertures 43 and by the free flow area 42.

In the figures 4 to 6 different embodiments of the return air orifices 43 are shown as a plan view and in the installed position. In the figures, the same components are provided with the same reference numerals. The regulation of the recirculation mass flow in the annular gap 50 between the guide tube 41 and the holding tube 21 is effected either by a corresponding large or small free flow area 42 of the return air apertures 43. If a rather small flow area 42 is necessary, then, as shown in FIG entire aperture 43 are housed within the gap. If, in contrast, a large flow area 42 is necessary, only individual interfering surfaces or diaphragm elements 55 of the diaphragm 43 in the annular gap Patz, which are connected to one another via a retaining ring 44 (see FIG. 5), are found. These two described variants of the aperture 43 need not be symmetrical, but may also have a significant asymmetry. This variant of a return air diaphragm 43 is shown in FIG. 6. The asymmetric design is necessary if the aperture 43 not only has a purely throttling function, but also the profile of the flow between the holding tube 21 and the guide tube 41 is to be adjusted. This is necessary if the supply of air into the annular gap 50 is not uniform across the flow channels, but e.g. from one direction is much more pronounced. In this case, the flow from this direction must be throttled considerably more strongly in order to achieve a uniform flow through the annular gap 50.

Furthermore, it may also be advantageous if the hot air does not flow evenly. Such a desired asymmetric flow can likewise take place via the diaphragm shown in FIG. 6.

The embodiments of a return air diaphragm illustrated in FIGS. 4 to 6 have, in particular, the following structure.

4 comprises a retaining ring 44, which is arranged in the annular gap 50 between the guide tube 41 and the retaining tube 21 and which is provided with six retaining webs 47, which respectively engage in a fixing slot 48, which is formed on the guide tube 41. As a result, the Rückfuhrluftblende 43 is securely held on the guide tube 41.

The Rückfuhrluftblende 43 shown in Figure 4 further comprises an inner ring 45 which is also disposed in the annular gap between the guide tube 41 and the holding tube 21 and which rests with its inner annular surface on the holding tube 21. The inner ring 45 is connected via connecting webs 46 with the retaining ring 44, which extend in the radial direction with respect to the axis of the holding tube 21. By the retaining ring 44, the inner ring 45 and the connecting webs 46, the free flow surface 42 of the return air vent 43 is fixed or arcuate windows are defined, which define the free flow surface 42. The retaining ring 44, the inner ring 45 and the connecting webs are interpreted in terms of their dimensions depending on the desired free flow area 42.

The illustrated in Figure 5 embodiment of a Rückführluftblende 43 includes a retaining ring 44 which rests against the outer peripheral surface of the guide tube 41 and branch off from the radially inwardly retaining webs 47, the retaining slots 48 of

Leitrohrs 41 durchgrei fen. In the present case, six retaining webs 47 merge in each case in the annular gap between the retaining tube 21 and the guide tube 41 into an aperture element 55, which partially fills the annular gap 50 and has an arcuate basic crack. The diaphragm elements 55 each have a support web 51, which is supported in the radial direction on the peripheral surface of the holding tube 21.

The diaphragm elements 55 cover the annular gap 50 only proportionately, so that a free flow area 42 for the return air remains between adjacent diaphragm elements 55 and between the individual diaphragm elements 55 and the retaining tube 21. Depending on the desired free flow area 42, the diaphragm elements 55 can have different dimensions.

FIG. 6 shows an embodiment of a return air diaphragm 43, which comprises an outer retaining ring 44, which bears against the outer circumferential surface of the guide tube 41 and projects from the radially inward support webs 47, which pass through the retaining slots 48 of the guide tube 41. Two of the retaining webs 47 go inside the annular gap 50 between the guide tube 1 and the holding tube 21 in aperture elements 55 over, which correspond to the aperture elements of Figure 5. The four other retaining webs 47 merge into a diaphragm part ring 52, which extends over an angular range of about 170 ° and is also supported on its inner side in the radial direction via support webs 51 on the outside of the retaining tube 21. The aperture ring 52 is provided with slots 53 and / or holes 54. Due to the dimensions of the diaphragm elements 55 and the diaphragm part ring 52, the free flow area 42 is fixed, which can be provided by the Rückführluffblende 43.

Claims

New claims

1. Receiver of a solar energy production system (100), comprising a support structure (7) which carries on a receiver front side a plurality of absorber modules (1 1), each comprising a holding tube (21) in such a guide tube (41) of the support structure (7) engages that between the holding tube (21) and the guide tube (41) an annular gap (50) is formed through which flows during operation for cooling the support structure (7) and / or the respective absorber module (1 1) return air to the receiver front side, characterized in that in at least one of the annular gaps (50) at least one throttling Rückführluftblende (43) is arranged, which defines a mass flow of the return air, which flows through the respective annular gap (50) to the receiver front.

2. Receiver according to claim 1, characterized in that the Rückführluftblende (43) comprises at least one retaining ring (44) which is fixed to the relevant guide tube (41) and / or the respective holding tube (21).

3. Receiver according to claim 2, characterized in that the retaining ring (44) within the annular gap (50) is arranged.

4. Receiver according to claim 2 or 3, characterized in that the retaining ring (44) surrounds the guide tube (41).

5. Receiver according to one of claims 2 to 4, characterized in that the

Return air diaphragm (43) has an inner ring (45) which is disposed within the annular gap (50) between the holding tube (21) and the guide tube (41) and on at least at least one connecting web (46) with the retaining ring (44) is connected.

6. Receiver according to one of claims 2 to 5, characterized in that of the retaining ring (44) in the radial direction at least one holding web (47) protrudes, which engages in a fixing slot (48) of the guide tube (41).

7. Receiver according to one of claims 1 to 6, characterized in that the

Return air diaphragm (43) comprises at least one diaphragm element (55) which partially fills the annular gap (50).

8. Receiver according to claim 7, characterized in that the diaphragm element (55) has a curved floor plan.

9. Receiver according to claim 7 or 8 in conjunction with one of claims 2 to 6, characterized in that the diaphragm element (55) via the retaining web (47) to the retaining ring (44) is connected.

10. Receiver according to one of claims 7 to 9, characterized in that the diaphragm element (55) has at least one support web (51) which is supported in the radial direction on the holding tube (21).

1 1. Receiver according to one of claims 1 to 10, characterized in that in the annular gap (50) at least two preferably identical return air apertures (43) are arranged, which are twisted in U mfangsrichtung each other.